Gorée is comfortable from November to March, when the dry season brings cool mornings, warm afternoons, and clear ferry crossings. December and January are the most pleasant — daytime temperatures around 25 C, very little rain, and the harmattan wind sometimes hazing the view of Dakar across the water.
April and May begin to heat up, and the summer rainy season (June to October) is hot, humid, and prone to sudden tropical downpours. Avoid the middle of the day in any season — the island has very little shade and the heat radiating off the stone walls is intense between 11am and 3pm. Aim for the first ferry of the morning or the late-afternoon crossing.